Nylon bristle resembling natural bristle



June 20, 1967 w. SAWKIW 3,325,845

NYLON BRISTLE RESEMBLING NATURAL BRISTLE Filed Feb. 26, 1965 2Sheets-Sheet T INVENTOR. //45 2 ,dkw/(m/ I I m,

ATTORNEY June 20, 1967 w s w w 3,325,845

NYLON BRISTLE HESEMBLING NATURAL BRISTLE Filed Feb. 26, 1965 2Sheets-Sheet 2 lNVENTO/Z WASVL SAWK/W A TTORNEV we re.

Patented June 20, 1967 3,325,845 NYLON BRISTLE RESEMBLING NATURALBRISTLE Wasyl Sawldw, Troy, N.Y., assignor, by mesne assignments, toInternational Playtex Corporation, a corporation of Delaware Filed Feb.26, 11965, Ser. No. 435,522 11 Claims. (Cl. 15-159) This inventionrelates to bristles for brushes, and more particularly, is directed tosynthetic filaments useful as bristles in brushes and to a method ofmaking such filaments.

The superiority of natural bristles over synthetic bristles forproviding brushing elements has long been recognized. This longrecognition has led many to attempt making synthetic bristles whichwould approach the cleansing and water retention ability of naturalbristles but such has not, until my present invention, beenaccomplished.

By my invention, I have provided a monofilament of synthetic materialwhich has surface characteristics of natural bristles. The syntheticmonofilament has randomly scored, indented and raised surface portionsand from random sites on the surface of the filament are fingerlikeprojections. The surface skin caused by case hardening inherent fromextrusion of a synthetic filament is removed or partially removed inareas defining a random pattern over the surface of the extrudedsynthetic filament. Furthermore, the surface of the synthetic filamentof my invention, in addition to being generally roughened, has numerousminute finger-like projections extending from the terminal ends of someof the random score lines impressed upon the synthetic filaments wherecomplete removal of the synthetic material from the score line does nottake place.

Because of these minute finger-like projections, the synthetic filamentsof my invention acquire a surface characteristic which is best definedas pubescent, i.e., covered with fine hairs.

This pubescent surface characteristic of the synthetic filaments of myinvention along with the irregular and random pattern of score linestherein provide for the first time a synthetic bristle useful forbrushes which is equal to or surpass-es the heretofore superiorqualities of a natural bristle. Since the skin of case hardening hasbeen removed in random score lines in the synthetic bristle and becauseof its pubescent characteristic such that it no longer has a smooth,hard surface, more water and cleansing material can be held by theindividual bristle than has heretofore been possible.

Similarly, since former attempts to provide synthetic bristles ofirregular or roughened shapes have primarily involved the extrusion of asynthetic filament through a die having an irregular cross section(i.e., octagonal, starshaped, fluted etc.) and since such an extrudedfilament is usually made approximately twice the diameter to which it issubsequently stretched down, any contour which is forced into thefilament by the die, which initially has sharp edges, cannot be retainedbecause during the stretching operation the sharp edges break down orround off somewhat. According to my invention, the sharp edges areretained by the score lines and roughened surface of the syntheticfilament since they are cut into the preformed filament by my discoveryof suitable apparatus for making such cuts and by making such cutssubsequent to all p-reforming operations upon the filament. As such,sharp edges are retained in the scored filament which aid in thecleaning of surfaces or elements brushed with brushes made therefrom.

The following description is directed to toothbrushes employing thebristles of my invention for convenience only. It is to be understoodthat the bristles of my invention are equally adaptable to brushes ofall sorts such as hair-brushes, scrubbing brushes, paintbrushes, and thelike.

In order that the invention is even more readily understood, referenceshould be had to the accompanying drawings and following specificationwherein there are illustrated and described one embodiment and a methodof manufacture therefore, but it is to be understood that the inventiveconcept is not to be considered limited to the constructions disclosedexcept as determined by the scope of the appended claims.

Referring to the acompanying drawings:

FIGURE 1 is an enlarged perspective view of a synthetic filament havingsurface characteristics in accordance with the present invention.

FIGURE 2 is a greatly enlarged fragmentary plan view showing at one edgea longitudinal out through the surface of the synthetic filament of thepresent invention.

FIGURE 3 is an elevational view of suitable apparatus for forming thesynthetic bristles in accordance with the invention; and

FIGURE 4 is an enlarged elevational view of the bristle-carrying portionof a toothbrush embodiment using bristles of this invention.

FIGURE 5 is a side elevational view of a typical internal screw threadtap used in the method of this invention.

FIGURE 6 is a View in elevation of the right hand end of the internalscrew thread tap of FIGURE 5 showing the arrangement of the teeth.

FIGURE 7 is an enlarged elevational view of parts of two individualteeth of the internal screw thread tap of FIGURE 5.

Referring first to FIGURES 1 and 2, there is shown a monofilament ofsynthetic material generally designated by the numeral 10. Projectingoutwardly from the surface of the monofilament 10 are numerous,irregularly spaced and postioned finger-like projections 12. Thesefinger-like projections 12 are themselves or irregular, crooked shapesand of varying cross sections presenting an overall irnpression of apubescent surface on the synthetic monofilament. As is also shown inFIGURES 1 and 2, the surface of the synthetic monofilament has numeroussharp edged irregularly shaped and sized depressed areas or scores, cutsor grooves 14 which extend in varying directions and to varying depthsover, around and into the synthetic monofilament 10. In some instances,the material cut or taken away from the score lines or grooves 14 in amanner more fully described hereafter forms a built-up area in the formof sharp edged irregularly shaped and directed mounds 16 on the surfaceof the monofilament 10. In other instances, the material partiallyremoved from the scored lines or grooves 14 forms the dendritic,fingerlike projections 12 described above.

In FIGURE 3, there is shown apparatus and a method for forming apreformed extruded synthetic monofilament into the syntheticmonofilament 10 of improved cleansing capabilities described above. Theapparatus consists of a motor 20 secured to a fixed surface 22 andadapted to rotate cutting elements 24 coupled to drive shaft 25 of saidmotor 20. Spaced from cutting members 24 and adapted to hold one or moretufts 26 of preformed extruded synthetic monofilaments perpendicular tothe longitudinal axis of cutting element 24 is a reciprocating member 28reciprocatable in a longitudinal direction transverse to thelongitudinal axis of said cuttting member 24.

In the embodiment shown in FIGURE 3, rotating cutting elements 24 aremetal cutting taps well known in the art for forming an internal screwthread. FIGURE 5 shows an internal screw thread tap typical of thoseused in the practice of this invention. The tap comprises a shank 52with a portion 54 which is squared off so that the chuck of a machinetool may grasp the tap firmly for rotation. A series of raised teeth 56are provided between which there are hollowed out areas or fiutes suchas 58, 60 and 6-2. The teeth are arranged in a helical pattern on theshank and each individual tooth has a sharp top edge 64 and a fiattriangular leading face 66. The top edge 64 is curved and the apex 68 ofthe front triangular face 66 is slightly higher than the apex of therear triangular f-ace, not shown. The triangular face 66 of each toothis relatively short and blunt as compared to the needles and sharpknives used by the prior art in treating bristles. Laterally spaced fromrotating taps 24 and perpendicular to the longitudinal axis thereof area plurality of tufts 26 of synthetic monofilaments, in this instance,inserted as bristle tufts in toothbrushes 30 in any manner well known inthe art. The bristle tufts 26 are maintained in a perpendicularrelationship to the longitudinal axis of the rotating taps 24 by beingclamped securely to reciprocating member 28 which is reciprocated in alongitudinal direction by a reversing motor (not shown) driving shaftsuitably rotatably journaled in fixedposition and adapted to drive rack42 secured to reciprocating member 28 through pinion 44. Reciprocatingmember 28 is maintained in a predetermined, fixed longitudinalrelationship by tongue track 46 mated to lateral grooves 48 inreciprocating member 28. As the tap rotates the bristle is contacted bythe front triangular face 66 and top edge 64 to deform and superficiallycut the surface of the bristle to form depressed and raised areas andhairlike projections as shown in FIGURES 1 and 2. This bristleconstruction is new and not shown in any of the prior art.

As taps 24 are rotated, the reciprocating assembly is positioned tocarry the tufts of bristles 26 back and forth longitudinally in adirection transverse to the longitudinal axis of rotating taps 24 and ata distance spaced from rotating taps 24 such that the tufts of bristles26 are dragged through the rotational path of the cutting edges 27 oftaps 24.

In the embodiment shown in FIGURE 3, wherein the synthetic monofilamentsare mounted as tufts 26 of bristles in a toothbrush 30 prior to beingcut by the rotating taps 24 to form the synthetic bristles of thepresent invention, varying the space between the rotational path of thecutting edges 27 of the taps 24 and the base of the bristles results inbeing able to vary the distance over which the pubescent, scored andraised surface extends along the length of the bristle. As shown,particularly in FIGURE 4, the pubescent, scored and raised surface ofthe bristles extends from the free end thereof toward the mounted orfixed end thereof a distance equal to about two-thirds the length of thebristle. Such treatment of the bristles is accomplished by adjusting thereciprocating member 28 holding the brush 30 in which the bristles aremounted a distance away from the lowermost rotational point of therotating cutting edges 27 such that the cutting edges of the rotatingtap 24 reach into the tuft of bristles a distance approximately equal totwo-thirds of their lengths. From the above, it can be readily seen thatthe distance to which the bristles are scored and cut by the rotatingmember can be widely varied. As described hereafter, the distance ofscoring can extend even the full length of the bristle.

While the embodiment shown depicts the cutting of bristles by arotatable member which bristles are mounted in a brush head, it is to beunderstood that synthetic monofilaments can be cut and scored by therotatable tap member prior to being mounted in a brush. In suchinstances, a plurality of synthetic monofilaments of any given lengthare secured at one end into bundles and mounted on a reciprocatingmember by any suitable means such as a clamp. The bristles are thendragged through the rotational path of the rotating tap members to anygiven depth in the bundle. This results in substantially the totallength of the synthetic monofilaments being cut and scored and thesurface thereof rendered pubescent. Following such treatment ofunmounted synthetic filaments, the bundle can then be removed from thereciprocating apparatus, cut into desired lengths for form ing tufts ofbristles for the brush desired and then mounted in the bristle-carryin gportion in the brush by any means well known in the art. In this manner,synthetic filaments forming the bristles of the brush obtain the scored,raised and pubescent surface characterizing the bristles of thisinvention substantially throughout their entire lengths.

Thus, by the above methods and apparatus, the present invention providesfor the first time, bristles of synthetic polymerized plastic materialswhich are equal to or surpass the ability of natural fibers, to hold andretain fluids and cleansing materials and for scouring and brushingsurfaces. Suitable synthetic polymerized plastics from which thebristles of the present invention can be made are nylon (a copolymer ofhexamethylenediamine and adipic acid), Lucite (a methyl methacrylatepolymer), cellulose acetate, cellulose acetate butyrate, polymerizedvinyl acetate and the like. In general, any polymerized plastic-likematerial which can be formed by extrusion into a long, thin monofilamentcan be used. However, in the practice of the present invention, theadvantageous results are obtained by extruding the synthetic plasticmaterial down to its finally desired dimensions prior to the cutting andscoring thereof by the apparatus above described. In this manner, allthe edges of the scored and built-up areas and finger-like projectionson the surface of the plastic monofilament retain their sharp, irregularconfigurations as formed. Accordingly, the bristles of the presentinvention accomplish better scrubbing and fluid retention than syntheticbristles heretofore available and in some instances, better than naturalbristles.

Often, synthetic filament material is supplied as a continuous filamenton a spool, or as a group of continuous filaments wound together On aspool in the fonn of a rope. In such instances, it might be desirable toscore the filaments continuously before they are cut into prescribedlengths in a bristling or bundling machine. The only modificationrequired to accomplish continuous treatment of a single continuousfilament or a rope of continuous filaments in accordance With thepresent invention is to pass the material over the top of one rotatingtap member and under another, preferably positioned close together. Inthis form, it is not required to have a reciprocating mounting memberfor a bundle of filaments. Again, it is seen that this method producessynthetic filaments which obtain a pubescent surface substantiallythroughout their lengths such that when they are mounted as bristles inbrushes, the bristles also have pubescent surfaces along their entirelengths.

It is to be understood that while the specific apparatus described formaking bristles of the present invention depicts stationary rotatingcutting elements through which synthetic filaments are dragged by areciprocating mounting member, the same results can be achieved byhaving the rotating cutting elements reciprocate back and forth throughthe synthetic filaments mounted on a stationary member, or by havingboth the cutting elements and the mounting member holding the syntheticfilaments each reciprocate back and forth in opposite directions. It isonly necessary that there be moving contact between the cutting elementsand the bristles to be treated. Further, while reciprocating motion hasbeen specifically described and illustrated, and continuous linearmotion has been described, arcuate motion, as by a pendulum or rockingarm, can similarly be employed.

While I have described my invention with particular reference to aspecific toothbrush embodiment, it is to be understood, that it is notto be limited thereto, but is to be construed broadly and restrictedsolely by the scope of the appended claims. Also, while I have describedmy invention with particular reference to specific apparatus for formingthe same, it is readily apparent that various changes, alterations, andmodifications therein can be made without departing from the spirit andscope of the invention as defined in the appended claims.

I claim:

1. In a brush having a bristle-carrying portion and a plurality of tuftsof bristles fixed therein, the improvement comprising bristles of asynthetic plastic material, each bristle consisting of a monofilamenthaving a pubescent surface, the surface of said monofilament beingfurther characterized by having sharp edged irregularly spaced, randomlydirected, depressed areas of varying sizes and shapes and sharp edgedirregularly spaced, randomly directed, raised areas of varying sizes andshapes intermediate said depressed areas.

2. The invention of claim 1 wherein said synthetic plastic material isselected from the group consisting of nylon, Lucite, cellulose acetate,cellulose acetate butyrate and polymerized vinyl acetate.

3. The invention of claim 1 wherein the pubescent, depressed and raisedsurface of said synthetic monofilament extends from the free ends ofsaid bristles toward the fixed ends thereof a distance equal to abouttwo-thirds the length of said bristles.

4. A toothbrush as defined in claim 1.

5. A toothbrush as defined in claim 2.

6. A toothbrush as defined in claim 3.

7. The method of making brush bristles of a synthetic plastic material,said bristles having a pubescent, randomly and irregularly scored andraised surface, said method comprising the steps of (1) extruding aplastic material into a monofilament of predetermined thickness, and (2)scoring said monofilament with a series of helically arrangedlongitudinally spaced rotating cutting elements by maintaining relativecontacting motion between said monofilament and said rotating cuttingelements, said relative contacting motion being in a directiontransverse to the longitudinal axis of said spaced rotating cuttingelements, each of said cutting elements having a flat triangular frontface and a sharp top edge.

8. The method of making brush bristles of a synthetic plastic material,said bristles having a pubescent, randomly and irregularly scored andraised surface, said method comprising the steps of (1) extruding aplastic material into a monofilament of predetermined thickness, (2)securing a plurality of said extruded monofilaments at one end thereofinto a bundle, and (3) scoring said monofilaments with a series ofhelically arranged longitudinally spaced rotating cutting elements bymaintaining relative contacting motion between said bundle ofmonofilaments and said rotating cutting elements, said relativecontacting motion being in a direction transverse to the longitudinalaxis of said spaced rotating cutting elements, said bundle beingmaintained substantially perpendicular to the longitudinal axis of saidspaced rotating cutting elements, each of said cutting elements having afiat triangular front face and a sharp top edge.

9. The method as defined in claim 8 wherein said monofilaments areformed into bundles and secured at one end by mounting a pluralitythereof into the bristlecarrying portion of a brush.

10. The method as defined in claim 8 wherein said relative contactingmotion is directed in a plane such that the path of rotation of saidspaced cutting elements extends into said bundle from the free ends ofsaid monofilaments a distance equal to approximately two-thirds thelength of said monofilaments.

11. The method of making brush bristles by roughening a monofilament ofhigh molecular weight polymeric whereby the monofilament resembles anatural bristle which comprises the steps of:

(1) providing an extruded monofilament of selected polymeric materialhaving a predetermined thickness;

(2) providing a selected number of deforming cutting tools having a basewith an outwardly projecting, raised, short in height cutting surfacewhich has a substantially flat face and a sharp top edge;

(3) causing relative contacting motion between the monofilament and thecutting surface, said relative contacting motion being in the directiontransverse to the longitudinal axis of said filament so that the flatface of the cutting surface hits the side of the filament;

(4) to roughen the side wall surfaces of the monofilament by cutting andscoring the individual filament along such side wall surfaces with thecutting surface;

(5) continuing the contacting of the cutting surface with themonofilament until the desired degree of roughening is obtainedwhereupon the side wall surfaces of the monofilament are provided with:

numerous sharp edged, irregularly shaped and sized, randomly positioned,depressed areas and raised areas which extend in varying directions andto varying extent over, around and on the monofilament, and numerous,sharp edged, randomly positioned finger-like projections of irregular,crooked shapes and of varying crosssections presenting an impression ofa pubescent surface, whereby the roughened monofilament is adapted tohold and retain water and cleansing materials similar to a naturalfilament, and

(6) removing the contact between the monofilament and the cuttingsurface.

References Cited UNITED STATES PATENTS 1,773,969 8/1930 Dreyfus et al.15159.1 2,110,371 3/1938 Radford 161180 2,245,191 6/1941 Guenther et al.161180 X 3,112,160 11/1963 Rush 161-180 FOREIGN PATENTS 1,043,990 6/1953 France.

713,188 8/1954 Great Britain.

897,404 5/1962 Great Britain.

941,679 11/ 1963 Great Britain.

383,545 1/1965 Switzerland.

PETER FELDMAN, Assistant Examiner.

1. IN A BRUSH HAVING A BRISTLE-CARRYING PORTION AND A PLURALITY OF TUFTS OF BRISTLES FIXED THEREIN, THE IMPROVEMENT COMPRISING BRISTLES OF A SYNTHETIC PLASTIC MATERIAL, EACH BRISTLE CONSISTING OF A MONOFILAMENT HAVING A PUBESCENT SURFACE, THE SURFACE OF SAID MONOFILAMENT BEING FURTHER CHARACTERIZED BY HAVING SHARP EDGE IRREGULARLY SPACED, RANDOMLY DIRECTED DEPRESSED AREAS OF VARYING SIZES AND SHAPES AND SHARP EDGED IRREGULARLY SPACED, RANDOMLY DIRECTED, RAISED AREAS OF VARYING SIZES AND SHAPES INTERMEDIATE SAID DEPRESSED AREAS.
 7. THE METHOD OF MAKING BRUSH BRISTLES OF A SYNTHETIC PLASTIC MATERIAL, SAID BRISTLES HAVING A PUBESCENT, RANDOMLY AND IRREGULARLY SCORED AND RAISED SURFACE, SAID METHOD COMPRISING THE STEPS OF (1) EXTRUDING A PLASTIC MATERIAL INTO A MONOFILAMENT OF PREDETERMINED THICKNESS, AND (2) SCORING SAID MONOFILAMENT WITH A SERIES OF HELICALLY ARRANGED LONGITUDINALLY SPACED ROTATING CUTTING ELEMENTS BY MAINTAINING RELATIVE CONTACTING MOTION BETWEEN SAID MONOFILAMENT AND SAID ROTATING CUTTING ELEMENTS, SAID RELATIVE CONTACTING MOTION BEING IN A DIRECTION TRANSVERSE TO THE LONGITUDINAL AXIS OF SAID SPACED ROTATING CUTTING ELEMENTS, EACH OF SAID CUTTING ELEMENTS HAVING A FLAT TRIANGULAR FRONT FACE AND A SHARP TOP EDGE. 